As is well-known to experts in the field, rolling mills have the function of reducing the thickness of raw materials (whether they be steel, aluminium or other material) to the required dimension.
Rolling mill cylinders are designed for transferring the load necessary for the deformation of the material from the fixed structure (rolling mills cage) to the strip.
During the rolling mill process, the loads generated by direct contact with the strip or with other cylinders (in the case of intermediate and resting cylinders), accidental stress and, in many cases, exposure to high temperatures, produce phenomena of wear, fatigue and various types of damage in the same cylinders. These phenomena, of a mechanical and thermal origin, deteriorate the surface of the cylinders and, on the one hand, cause faults such as, for example, errors in the form, dents or variations in the roughness which reduce the quality of the strip and consequently its sales price. On the other hand, they can also cause faults of a structural type (such as burns and cracks, for example) which can lead to catastrophic events, such as the breakage of the cylinder during rolling mills process, which lead to even more serious economic losses.
The cylinders are consequently dismantled cyclically from the cages, their geometrical characteristics are measured, analyzed with Non-Destructive Control (NDC) techniques and re-conditioned by grinding before being re-admitted to operation. As a result of the high investment necessary for a set of cylinders, each innovation which reduces measurement and re-conditioning times, increases cylinder precision and reliability, and prolongs their operative life, results in a net and tangible profit for the laminate producer.
In particular, the current prospect of devices for revealing the geometry of operative cylinders is characterized by particularly complex and costly solutions in which the detection of the geometry of the cylinder is effected by machines with multiple measuring points with maintenance requirements, due to their complexity, which are also onerous.
A solution of this type is proposed in WO2006084072.
Furthermore, U.S. Pat. No. 6,159,074, or JP 8285504 describe gauges with two measurement points capable of measuring form errors based on two reading instruments arranged in diametrically opposite positions or on a single instrument assisted by a fixed swallowtail. In these cases, however, the constructive simplicity and limited cost are achieved to the detriment of the precision, measurement reliability and critical nature and complexity of the calibration of the instrument.